Tilted cold dark matter models confront the cosmic microwave background and the galaxy peculiar velocity field

We study tilted cold dark matter (CDM) models, that is OMEGA0 = 1 models with a primordial spectral index n less than or similar to 1. We test these models against three experiments on the cosmic microwave background anisotropy at 7', 3-degrees, and 6-degrees, and against measurements of galaxy peculiar velocities on large scales. These observations together suggest that the whole class of tilted CDM models with n less-than-or-equal-to 1 can be ruled out, for any value of the biasing parameter b.